Conventional power plants for the production of electric energy from controlled-fission nuclear reactions are today designed and constructed in such a way that all the main works which said power plants are comprised of, in particular the nuclear isle, the stream generators, the turbine/electric generator isle and the safeguard buildings, are located above the soil surface.
Safety and security of these power plants that are considered as very dangerous targets, particularly after the Chernobyl power-plant disaster and the terrorist attacks to the Twin Towers of New York, are based on various systems. In particular, their safety is obtained by using redundant structural solutions (for both plant engineering and building works), separating circuits for heat exchange and cooling, constructing with pre-assembling piping, adopting high constructive standards, protecting and multiplying safeguard buildings and applying extremely rigorous procedures for the management of plants and personnel.
However it is evident that such solutions are absolutely inefficient to protect a nuclear power plant against the most probable attacks, i.e. a launch of large aircraft filled with fuel or explosive, or even of rockets, towards the nuclear isle or pools containing spent nuclear fuel. These are scenarios that have become very realistic in the last years.
It is evident that events of this kind would generate what military experts cell “dirty bombs”, whose effects, even if not so destroying like those of a nuclear bomb, would be anyway so dangerous to pollute with following fall out large areas, up to thousands of square kilometers, with a result of making these areas inhabitable for centuries.
Several solutions have been proposed by skilled in the art from the 60's. Even if such solutions were not specifically designed to withstand extreme terrorist attacks that were not foreseeable in the past, they aimed to reach high safety levels against accidental releases of radioactive materials, by locating a nuclear reactor in underground caverns that were excavated for this purpose.
However, the proposed solutions do not allow sufficiently advantageous effects to be achieved so that their adoption can be suggested, on the one hand for the safety, on the other for the overall economic cost. A solution for an underground nuclear power plant is disclosed for example in the patent RU No. 2.273.901.
The solution proposed by the present invention fits in this context, which provides an embodiment of a nuclear power plant able to assure:                a strong reduction of the cost needed for decommissioning the nuclear power plant by applying innovative procedures, the decommissioning being certain at the end of its life service;        an absolute protection of population and environment outside the nuclear power plant from radioactive releases due to either accidental causes or any terrorist attacks or catastrophic natural events;        a final supersafe storage of low-intermediate level radioactive wastes that are produced during the operation of the nuclear power plant, by avoiding the handing in the soil surface of such radioactive wastes towards main treatment/conditioning/disposal centres;        an interim, insuperably safe storage of spent fuel, of high-level long-life radioactive materials and, if necessary, of spare rods for refuelling the nuclear reactor;        a consequent better relationship with the population, and then a higher certainty of the initial investments.        